1. Field of the Invention
The invention relates to a shearing machine with shearing heads or drums rotatably mounted on a luffable shearing arm and with a loading ramp or a conveyor running in the direction of the heading face for receiving and conveying away the sheared material. The loading ramp or the conveyor is supported displaceably in the longitudinal direction of the shearing machine on the machine frame and the horizontal luffing axis of the shearing arm runs transversely to the longitudinal direction of the machine and is mounted adjustably relative to the machine frame in the longitudinal direction of the machine. The adjusting movement of the horizontal luffing axis of the shearing arm is coupled to the adjusting movement of the loading ramp or of the conveyor.
2. Description of the Related Art
Austrian Patent Specification 386,457 has disclosed a shearing machine of the type mentioned at the beginning. In the case of this known design of the shearing machine, the object was to permit an exact positioning of the loading ramp or of the conveying-away means even when the shearing machine is not moved along. However, the positive coupling, provided in Austrian Patent Specification 386,457, of the displacing movement of a conveyor with the displacing movement of the luffing axis of a shearing arm of a shearing machine cannot always be considered optimal. In particular, during break-in shearing, i.e. at the beginning of a new shearing operation at the heading face. During break-in shearing, in particular whenever the shearing head is advanced into the heading face close to the roof, at first a certain break-in depth is prescribed, which is intended to apply subsequently for the downward shearing at the heading face. In particular in the case of drum shearing machines, the preselected break-in depth is always maintained during downward luffing of the shearing arm in the vertical direction and, with a positive coupling of the movement of the loading ramp with the breaking-in or penetrating movement of the shearing head or of the shearing drum. The breaking-in or penetrating operation may be hindered by the loading ramp, since for example, when penetrating close to the roof, the loading ramp cannot be driven into the heading face far enough at the floor. In the case of such an operation, the known positive coupling of the displacing movements therefore requires an adjustment in which the loading ramp is forced always to remain a certain amount behind the shearing head, in order not to hinder the shearing work during break-in shearing.
It may be advantageous in particular in the case of lightweight machines to anchor the machine in the roadway and a moving-along of the machine itself for the purpose of break-in shearing is not of advantage, not least because, during a moving-along of the machine itself, to achieve the necessary break-in or penetrating depth, an exact control of this depth is not readily achieved. For this reason, on the machine known from Austrian Patent Specification 386,457 as well, a design of the mounting of the jib or shearing arm was chosen which permits displacement of this mounting in the direction of the heading face with the machine at a standstill.